An overlay network is built on top of an underlying network (i.e., the underlay network) infrastructure to enhance the functionality of the underlay. Among other things, overlay networks may be used to support multi-tenancy as well as improve speed, flexibility, scalability, and manageability of application deployments, and, for example, to extend the reach of Layer 2 domains across data center pods, domains, and sites. VXLAN (Virtual Extensible LAN), for example, is a Layer 2 overlay scheme that is overlaid over a Layer 3 network. VXLAN uses VXLAN tunnel endpoint (VTEP) devices to map tenants' end devices to VXLAN segments and to perform VXLAN encapsulation and de-encapsulation.
One class of devices (referred to as a “multicast tunnel end-point” devices or “MC TEPS”) can participate in IP multicast routing in the underlay and can map client- and overlay-multicast groups in the underlay. Multicast-protocol-support facilitates a more efficient delivery of traffic for one-to-many communications in allowing traffic to be sent to a set of network devices that have joined the multicast group.
A second class of devices (referred to as “Head End Replication”) only supports head-end replication of the multi-destination traffic in which client- and overlay-multi-destination traffic are replicated, by the head-end replication device, and sent as separate unicast copies to each remote tunnel end-point device having listeners for the multicast channel. Head end replication is an encapsulation and de-capsulation scheme (rather than a tunnel type) that uses static mappings of VTEPs for the management of broadcast, unicast, multicast, and unknown packets.
In certain circumstances, it is desired to have multicast only supported (MC TEP) devices and head end replication only supported (HER TEP) devices interoperate with each other.